DEVELOPING AN EXPERIMENTAL ALL-SKY CAMERA BASED ON THE RASPBERRY PI

COMPUTER BOARD

Ed Kalin – March 1, 2014

Westport Library Maker-In-Residence

Goals as Maker-In-Residence

Develop three experimental all-sky cameras Based on the Raspberry Pi computer and

camera module Use inexpensive materials (such as PVC,

HDPE, 3D-printed plastic) Document the work Plan a DIY workshop around at least one of

the cameras

What is an all-sky camera?

A digital camera that can capture photographs or videos of the entire arc of the sky within a single frame

What can you use it for?

Record meteor or satellite trails Time-lapse cloud motion sequences Migrating flocks of birds Aircraft (or perhaps even UFOs!) Weather events The motion of astronomical features such as

the sun, moon, planets and stars And more...

What is a Raspberry Pi?

“The Raspberry Pi is a credit-card-sized single-board computer developed in the UK by the Raspberry Pi Foundation with the intention of promoting the teaching of basic computer science in schools.” (credit: wikipedia)

Happy Second Birthday

Raspberry Pi was introduced two years ago “today” (February 29, 2012)

Model A Model B

Why use the Raspberry Pi?

Small (embeddable form-factor), but capable Low-power consumption Popular (over 2.5 million produced) GPIO ports simplify electronic interfacing Easy network connectivity for moving data On-board camera module connector Inexpensive (starting as low as $25 for basic board) Open-source, Linux-based operating system Extensive community support

Raspberry Pi camera module

Add-on 5 megapixel camera board Native resolution: 2592 x 1944 pixel static

images 1080p30, 720p60 and 640x480p60/90 video Small size and weight: 25mm x 20mm x 9mm,

weighs just over 3g Inexpensive (approx. $25) Operation controlled by software

Camera module (continued)

Additional electronics to develop

Internal and external sensing (day/night, temperature, humidity)

Location (GPS) Alignment (true north?) Battery health monitoring Power via network cable? Heated enclosure for stable environment Cooling needed in summer?

Gertduino add-on board

Arduino functionality interfaced to Raspberry Pi board for improved sensor access, RTC

Three different approaches

Camera #1 - equip a camera module with a super-wide-angle (fisheye) lens

Camera #2 - photograph an upward-facing mirrored dome

Camera #3: fuse the images from multiple cameras continuously staring at different sky sectors into a single image

Proof of concept image, Camera #1Raspberry Pi cam with fisheye adapter

Proof of concept image, Camera #1Nikon with fisheye adapter

A real-world all-sky camera example

Determine height and speed of incoming meteors: http://fireballs.ndc.nasa.gov/

Example 'professional' images

Some technical challenges – Camera #1

Resolution – JPEG, native sensor capabilities, vignetting

Lens quality – focus, optical aberrations, etc.

Exposure - Manual control, lens speed, camera sensitivity, electronic noise

Data storage – transmission rate, size

Performance – of camera, processor, network

Environmental hardening – rain/snow/ice, humidity, temperature, UV rays, condensation

Power – minimize consumption, AC vs. DC, battery life, safety

Technical challenges – Camera #1 (continued)

Software – computer vision, analysis, control UX - “headless” computer, usability Mechanical design issues – housing, mounting Easy access to electronics yet weather-

resistant Best siting for clear horizon makes access

difficult

Technical challenges – Camera #2

Mechanical design Optical design Obstruction of image by camera mount

Technical challenges – Camera #3

Mechanical design Software – synchronization, image stitching Expense – start with eight-camera subset Data rate, size

Scheduled “Office Hours” outside the MakerSpace

Mondays, 6 PM – 8 PM Wednesdays, 3 PM – 5 PM Fridays, 1 PM – 3 PM Available at other times as well Snowstorm? All bets are off

Final Presentation

Sunday April 6th, 2 PM – 4 PM DIY workshop schedule(s) TBD

Credits

Raspberry Pi:

http://en.wikipedia.org/wiki/File:RaspberryPi.jpg

http://downloads.element14.com/raspberryPi1.html

Raspberry Pi Camera Board:

http://www.mcmelectronics.com/product/28-17733

Gertboard:

http://www.mcmelectronics.com/product/83-15656

Professional all-sky camera images:

http://www.beskeen.com/projects/allskycam/allskycam.shtml

http://www.company7.com/sbig/products/st237allsky.html

NASA's All Sky Fireball Network:

http://fireballs.ndc.nasa.gov/

The End